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Coal Sack (9,670 of 18,816)

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Coal Sack

Coal Sack, Coalsack, Coalsack Nebula, Caldwell 99

RA: 12h 31m 19s
Dec: −63° 44′ 36″

Con: Crux
Ch: MSA:1002, U2:450, SA:25

Ref: SIMBAD

(reference key)

Type: dark nebula

Mag: –

Size: 400′ x 300′
PA: ?

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Sketches  (2)

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Photos  (2)

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Published comments

Bailey

The Coal Sack is clearly seen on Plate 5 of Solon I Bailey's photograph from "The Southern Milky Way", Annals of Harvard College Observatory, Vol 72, No. 3. "The Coal Sack is seen here to be very irregular in shape and to be much richer in stars than non-galactic regions. It appears dark to the eye only by contrast with the adjacent brilliant portions of the Milky Way. Many dark lanes are shown on this plate. One of these forms a long extension to the Coal Sack in a south preceding direction." To Plate 6, Bailey comments: "The most striking feature of this region are the rifts in the Milky Way south of, and following, Alpha Centauri. The former somewhat resembles the Coal Sack. Both this and the great break following alpha Centauri are well shown in the drawings of Gould and others."

Photo index

Photo index by Jim Lucyk: Astronomy mag. 5/85 p35, Astronomy mag. 9/78 p28, Astronomy mag. 7/87 p60, Sky Catal. 2000 (Vol 2, 1985) pxxvii, Burnhams V2 p734, Observer's Guide (Astro Cards) 11-12/87 p18

Modern observations

Hartung, E.J. (1968)

"Crux lies almost wholly in the Milky Way which is very bright in this region and so renders conspicuous the large irregular dark nebula immediatley Sf known as the Coal Sack. This dust nebula is about 7° x 4° and lies at a distnace of 170pc ... Projected on it is a small star CPD 3376 mag 6.5, which on a clear dark night is distinctly visible to the unaided eye and may therefore be used as a test object.

Phill Harrington

"...the most famous naked-eye dark nebula in the entire sky. Covering an area approximately 5° x 7°, it looks like a huge dark hole in the radiant star clouds of the Milky Way just easy of Acrux. It mroe than fills the field of most binoculars. While most amateurs see the Coalsack as a homogeneous black patch, intricate filamentary detail may be spotted throughout by sharp-eyed observers. However, one must wait for a dark night before these delicate features will reveal themselves. At a distnace estimated to be about 550 light years away, the 60-light-year wide Coalsack is believed to b the closest obscuring nebulosity to Earth."

Contemporary observations

Auke Slotegraaf

1997 April 14

1997 April 14, 02:00 - 04:00: Naked eye, 40-degree altitude; appears like a large, dark puddle in the milky way, alongside alpha and beta Crucis. It's just about the right size for the LMC to fit in, and looks as if the LMC was torn off here and cast aside. The Jewel Box lies right on the edge of the Coal Sack. Pointed tear-drop shape, as long as alpha-gamma Crucis.

Kerneels Mulder

2009 January 24

Date and Time: 24 January 2009, 21:40
Location: Prince Albert (Western Cape, South Africa).
Instrument: Naked eye
Eyepieces: N/A
Sky Conditions: Seeing: 5/10. Transparency: Average
Windy

Naked eye: Very large dark nebula visible as a dark oval patch to the S of Mimosa and E of Acrux in Crux. Appears to be around 5°x 4° in size. Averted vision shows 1 star within the dark patch about 2° below Acrux.

Appears to be uniformly dark and nicely silhouetted by background glow of the Milky way, making it easily visible once dark adapted.

Magda Streicher

(no date)

Opaque dark roundish naked-eye oval shape nebula neighbour's the Southern Cross. Inside half way from the middle on way to A Crux the close star right next of the dark nebula a faint star can be seen. I estimate the nebula about 7 decrees in size.

Gary Lillis

2008 May 02, 21:45

Southwell, Timm's farm.

8x21 binoculars

Conditions: Very stable, clear, good.

Size=6.5x5 degrees. Edges sharply defined, few stars superimposed M6.9-M8.2 (8x21 binoculars), many stars on the boundary 7th-8th magnitude. Naked eye reveals sharp edges with no stars superimposed on the nebula. Nebula stands out well against the immensely starry background. The Coalsack is isolated in the region between alpha Crucis and beta Crucis. The Coalsack is extremely dark due to the contrast with the bright Milky Way, and has a slightly elongated shape towards the south.

Pierre de Villiers

2016 February 05, Friday

Location: Bonnievale SSP

Coal Sack dark nebula, m = 0!

Size 200' x 150' vs. 375' x 250' in catalogues!

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